In the human body, the carpal tunnel or carpal canal is the passageway on the anterior side of the wrist that connects the forearm to the middle compartment of the deep plane of the palm. The tunnel includes bones and connective tissue. Several tendons and a median nerve pass through it. The carpal tunnel is narrow, and when, for various reasons, the space within the tunnel is reduced or the volume of contents of the tunnel is increased, the effective narrowing of the carpal tunnel with respect to its contents often results in the elevated carpal tunnel pressure, which leads to the median nerve becoming entrapped or compressed—a medical condition known as carpal tunnel syndrome (CTS). This compression causes paresthesia, pain, numbness of the thumb, index, long, and radial half of the ring finger and other symptoms in the distribution of the median nerve. The scientifically established treatment of the carpal tunnel syndrome includes surgery to cut the transverse carpal ligament to release the carpal tunnel pressure.
Although the close relationship of carpal tunnel pressure with median nerve dysfunction has been reported, the current methods for measuring the tunnel pressure are invasive, such as, for example, the use of a catheter inserted into the carpal canal to monitor the pressure. A noninvasive method for quantifying the carpal tunnel pressure and, in general, the pressure of any closed bodily compartment that has a tendon remains desirable.